Device and method for producing three-dimensional objects

Abstract

Device (1) for producing three-dimensional objects (2) by successively solidifying layers of a radiation-solidifiable building material (3) at the locations corresponding to the respective cross-section of the object (2), - with a housing (4) enclosing a process chamber (5), - a construction container (6) housed therein, - an application device (7) for applying layers of the building material (3) to a support device (8) in the building container (6) or a previously formed layer with a coating element (9), wherein - the construction container (6) is provided with an inert gas-tight cover device (22) by means of which the construction opening of the construction container (6) can be covered in an inert gas-tight manner when the construction container (6) is removed from the device (1), characterized in that - an inert gas lock (40) is arranged in the region of the at least one cover device (22), wherein - a cover device of a process chamber floor and the cover device (22) of the construction container (6) form two walls of the inert gas lock (40), wherein - an intermediate space (41) defined by these walls forms a lock chamber which is provided with an inert gas inlet, so that - the intermediate space (41) between the two cover devices (22) can be flooded with inert gas and / or can be subjected to an inert gas overpressure before at least one cover device (22) is opened.

Description

The invention relates to an apparatus and a method for producing three-dimensional objects by successively solidifying layers of a radiation-curable building material at the locations corresponding to the respective cross section of the object, with the further features of the preamble of claim 1.Such a device has a housing comprising a process chamber. A process chamber base usually accommodates a construction chamber with a height-adjustable platform, a metering container and an overflow container. An application device is movable over the process chamber bottom in order to apply build material conveyed from the dosing container as a thin layer in the region of the build container. Surplus construction material is conveyed beyond the region of the construction container and pushed into an opening of the overflow container.For solidifying the construction material, an exposure device is provided, which usually consists of a laser and a scanner device. The scanner device is connected to a processor and is therefore suitable for controlling a laser beam of the laser in a targeted manner via the construction surface, such that thin layers of the construction material can be melted or melted and solidify upon cooling.From DE 198 46 478 it is already known to design the construction container as a replaceable container and thus to make it removable from the device.DE 20 2013 009 787 U1 describes a system having a workpiece production section for producing workpieces by exposure of raw material powder layers to electromagnetic radiation or particle radiation, which system comprises an irradiation device and a process chamber sealable with respect to the ambient atmosphere, having a carrier for receiving a raw material powder and a workpiece produced from the raw material powder by a generative layer construction method, wherein the carrier is displaceable relative to the process chamber into a construction chamber with increasing overall height of a workpiece produced on the carrier.Furthermore, it is known to carry out generative construction processes in a protective gas atmosphere, i.e. during the construction process, inert gas is applied to the process chamber and thus also to the exposed region of the construction container and the further containers.The object of the invention is to design, starting from this prior art, a device with the features of claim 1 in such a way that a construction process can be carried out with higher quality and more safely. This object is achieved by the characterizing features of claim 1. Advantageous further developments of the invention are evident from the dependent claims.The core of the invention is considered to be at least the construction container provided with an inert gas-tight cover device, by means of which the construction opening of the construction container can be covered in an inert gas-tight manner when the construction container is removed from the apparatus, so that an inert gas atmosphere is maintained in the construction container for a longer time. Such a lid device ensures that the interior region of the construction container is not exposed to the atmosphere during or after removal of the container, i.e. defined conditions can be maintained in the interior region of the construction container, as far as temperature, temperature reduction or increase, gas pressure or further relevant parameters are concerned. In addition, it is avoided that explosive powder types can lead to damage to the environment and operating personnel due to contact with oxygen. The same applies to the construction surface opening in the process chamber base, under which the construction container is inserted. By means of a sealing device in this region, an inert gas atmosphere can be maintained permanently even in the interior region of the process chamber.In principle, different advantageous designs of cover device are conceivable. Either the cover means is a sliding cover or a roller cover, but it is also possible to insert one or more plates or plate element elements automatically or manually into the respective openings, which can be done, for example, by a glove box means on the device. The operator can insert lid devices arranged in the process chamber or introduced into the latter manually into the openings and seal them there. First, the cover devices would have to be inserted into the opening of the construction container, and then an opening in the process chamber bottom could be sealed off in an inert gas-tight manner. However, it is also conceivable to carry out the insertion of the cover devices fully automatically and in a positively controlled manner, so that it is ensured that an inert gas seal of the respective inner regions, namely inner regions of the construction container and inner region of the process chamber, is carried out before the start of the removal process of the construction container.The same also applies to further containers. A cover device corresponding to the cover device provided on the construction container, in a design as a sliding cover, roller cover, cover or plate element, is likewise possible on the metering container or on an overflow container. Here, the same structural features as in the construction container can be provided.In principle, it is within the scope of the invention to control the movements of the at least one cover device (on the construction container, on the process chamber bottom on a metering container or overflow container) by electric motor, hydraulically or pneumatically. According to the invention, an inert gas lock is arranged in the region of the at least one cover device. This means that either the cover device of the process chamber bottom together with the cover device of the construction container form two walls of an inert gas lock. The intermediate space is then the lock chamber, which is provided according to the invention with an inert gas inlet, so that the intermediate region between the two cover elements can be flooded with inert gas before opening the cover elements. For safety reasons, it can be provided to subject the intermediate space between the two inert gas lock cover elements to an excess pressure of inert gas.As far as the seals of the respective cover elements are concerned, it is advantageously possible to provide, for example, inflatable seals which bear very closely and sealingly against the respective edges of the openings or surfaces of the cover element or elements.In principle, it is advantageous to provide a module cover element if a plurality of containers are arranged next to one another in a removable construction module. Then all containers would be covered by a common cover element in an inert gas-tight manner. However, this does not necessarily mean that individual cover elements can not also be provided for the respective containers, so that they can be emptied, cleaned or the like separately without changing the inert gas filling state in adjacent containers.The invention is explained in more detail with reference to exemplary embodiments in the drawing figures. These show: FIG. 1 shows a schematic illustration of an apparatus with a process chamber, construction container, application apparatus, metering device, irradiation device and an overflow container according to the prior art; FIG. 2 shows a schematic illustration of a cover element which is designed as a sliding cover; FIG. 3 shows a schematic illustration of a cover element of a container which is designed as a rolling cover; FIG. 4 shows a schematic illustration of a construction container in which two cover elements lying one above the other form an inert gas lock; FIG. 5a is a representation of a construction container which can be placed under a process chamber base, wherein the openings in the process chamber base and in the construction container can be covered with separate cover devices (5b).Reference is first made to FIG. 1. There, a device 1 for producing three-dimensional objects 2 by successive solidification of layers of a build-up material 3 which can be solidified by means of radiation at the locations corresponding to the respective cross section of the object 2 is shown. The apparatus 1 has a housing 4 which encloses a process chamber 5 in which a construction container 6 is accommodated. Furthermore, an application device 7 of for applying layers of the building material 3 to a support device 8 in the building container 6 or a previously formed layer is provided, wherein the building device 7 comprises a coating element 9. Building material 3 is supplied to the application device 7 by a dosing device 10 with a dosing container 11.Above the process chamber 5, an irradiation device 12 is provided for irradiating layers of the building material 3 with a focused laser beam 13 at the locations corresponding to the respective cross section of the object 2, wherein the laser beam 13 is generated by a laser 14 and is conducted through a scanner 15 according to construction data stored in a computer to the construction field 16, in which a solidification of the thin building material layers takes place. In the exemplary embodiment shown, the construction container 6 is designed as a replaceable container and can thus be removed from the device 1. The same applies to the dosing container 11 and an overflow container 17, into which superfluous construction material 3, which could not be used for layer application, is discharged by the coating element 9.The construction container 6, the metering container 11 and the overflow container 17 are arranged under openings 18, 19 and 20 which are arranged in a process chamber base 21. The containers 6, 11 and 17 can either be inserted under the process chamber floor by suitable mechanical devices or can be raised by lifting devices and locked there. Essential for an exact construction of the object 2 is a precise attachment of the construction container 6 under the process chamber base 21.In the drawing figures 2-5, it is shown that the construction container 6 is provided with an inert gas-tight cover device 22, which seals the upper opening region 23, which as it were defines the construction area 16, in an inert gas-tight manner, provided that the construction container 6 is removed from the apparatus 1. Of course, the cover device 22 can also be closed when the construction container 6 is attached under the process chamber base 21 in the locked state, but no laser melting or laser sintering process is then possible.In FIG. 2, the cover device 22 is designed as a sliding cover, which in FIG. 2 can assume a closed position 22 aand an open position 22 b, which is pushed to the right. Sealing elements 24 of a suitable type ensure the inert gas tightness between the upper edge 25 of the construction container 6 and the cover device 22. It is also within the scope of the invention to also provide the construction surface opening 18 in the process chamber base 21 arranged above the construction container 6 with an inert gas-tight cover device 30, which seals the construction surface opening 18 in an inert gas-tight manner when the construction container is removed from the apparatus 1. The opening and closing movement of the cover devices of the construction container 6 and of the construction surface opening 18 in the process chamber base 21 can be positively controlled, i.e. they can be automatically closed and opened, so that it is avoided that the respective openings 18 and 23 can open when the construction container 6 is removed and inert gas can flow out or oxygen can flow into the inerting regions.FIG. 3 shows that the cover device 22 is designed as a rolling cover 33. FIG. 4 shows that a cover device 22 designed as a sliding cover 34 can be combined with a further cover device designed as a roller cover 33, so that an inert gas lock intermediate space 41 of an inert gas lock 40 is formed between the two devices 33 and 34. It is within the scope of the invention to attach or guide the lower cover device 22, namely the slide cover 34, to the construction container 6 and also attach the rolling cover 33 to the construction container 6 or alternatively attach or guide the rolling cover 33 under the process chamber base 21, so that the rolling cover 33 serves to close the construction field opening 18 in the process chamber base 21.It should also be mentioned that the lower cover element is also according to. FIG. 4 can be designed as a roller cover 33 and the upper cover element as a slide cover 34, it is likewise possible to combine two slide covers 34 or two roller covers 33 with one another or to combine one roller cover 33 or one slide cover 34 with plate-like cover elements, as are illustrated in FIG. 5.In FIG. 5 a, a construction container 6 is first shown in a lowered state, i.e. not yet connected to the process chamber base 21, the construction container 6 can be raised by a suitable device and placed exactly under the construction field opening 18 of the process chamber base 21 via the centering elements 45.In FIG. 5 b, the construction container 6 is connected to the process chamber base 21, as is the case in a construction process. The build area opening 18 is closed by a build area sealing plate 60. The opening portion 23 of the building container is sealed with a sealing plate 61. The sealing plates 60 and 61 can be introduced into their respective sealing position from above and locked there. An inert gas-tight seal is obtained by sealing elements 65, which seal the edge region of the two sealing plates 60, 61 with respect to the respective edges of the process chamber base 21 or of the construction container 6. These seals 65 can be designed as inflatable seals.It is also indicated in FIGS. 5 aand 5 bthat a pressure bottle keeps a mobile inert gas supply 70 ready, with which either the intermediate space 41 of the inert gas lock 40 or the inner regions of the containers 6, 11 or 17 are to be flooded. In principle, however, it is conceivable to couple the containers to inert gas supplies also in storage areas, so that the inert gas state can be maintained there over a long time during storage.Individual aspects of the invention are also evident from the following clause: 1. apparatus (1) for producing three-dimensional objects (2) by successive solidification of layers of a radiation-curable building material (3) at the locations corresponding to the respective cross section of the object (2),having a housing (4) enclosing a process chamber (5),a construction container (6) accommodated therein,an application device (7) for applying layers of the building material (3) to a support device (8) in the building container (6) or a previously formed layer with a coating element (9),a dosing device (10) having a dosing container (11) for supplying the building material to the application device (7),an irradiation device (12) for irradiating layers of the building material (3) at the locations corresponding to the respective cross section of the object (2) with a focused energy beam, in particular a laser beam, wherein the building container (6) can be removed from the device (1) either as a separate replaceable container or within a replaceable module, characterized in thatthe construction container (6) is provided with an inert gas-tight lid device (22) which seals the upper opening region (23) of the construction container (6) in an inert gas-tight manner in the state removed from the apparatus (1).2. Device according to Clause 1, characterized in that in the region of the construction surface opening (18) arranged above the construction container (6) located in the device, an inert-gas-tight cover device (30) is arranged in the process chamber base (21), said cover device sealing off the construction surface opening (18) in an inert-gas-tight manner when the construction container is removed from the device (1). 3.Apparatus according to Clause 1 or 2, characterized in that the opening and / or closing movement of the lid devices of the construction container (6) and / or of the construction surface opening (18) in the process chamber base (21) is positively controlled in such a way that, when the construction container (6) is removed (1) from the apparatus, the lid device(s) (22, 31) closes(s) and opens(s) when the construction container (6) is inserted into the apparatus (1). 4. The device according to clause 1-3, characterized in that the cover device(s) (22, 31) comprises(comprise) at least one slide cover. 5. device according to clause 1-3, characterized in that the cover device(s) (22) comprises(comprise) at least one rolling cover (33). 6.Device according to one of the preceding clause, characterized in that the cover device(s) (22) is(are) formed as at least one plate element which is(are) insertable into a sealing region of the construction container (6) and / or of the construction surface opening (18). 7. apparatus according to one of the preceding clause, characterized in that the movements of the at least one cover device (22) can be controlled by electric motor, hydraulically or pneumatically. 8 Device according to one of the preceding clause, characterized in that the opening or closing movement can be positively controlled by a mechanical control element on the at least one cover device (22) and / or on a holding device of the device (1) receiving the container (6, 11, 17). 9. device according to one of the preceding clause, characterized in that an inert gas lock (40) is arranged in the region of the at least one cover device (22). 10. The device according to clause 9, characterized in that the inert gas lock (40) comprises at least one first and at least one second inert gas-tight cover element, and the movement of the two cover elements can be controlled separately from one another or the cover elements can be brought into the sealing position separately from one another. 11 The device according to clause 10, characterized in that the inert gas intermediate space (41) between the first and the second cover element of the inert gas lock (40) has an inert gas inlet. 12th Device according to one of Clause 8 or 9, characterized in that the inert gas lock intermediate space (41) can be subjected to an excess pressure of inert gas. 13.Apparatus according to one of the preceding clause, characterized in that an overflow container (17) for unused build-up material (3) and / or the metering container (11) of the application apparatus (7) is (are) likewise designed as a replaceable container having an inert-gas-tight cover device. 14. device according to one of the preceding clause, characterized in that all containers (6, 11, 17) of the device (1) are covered by the same cover element. 15. Device according to one of the preceding clause, characterized in that the at least one cover element of the device (1) is prestressed in a closed position which is tight with inert gas by means of at least one elastic element. 16.Device according to one of the preceding clause, characterized in that the opening movement of the respectively lower cover elements of the inert gas locks (40) of a plurality of containers (6, 11, 17) can be controlled separately. 17. apparatus according to one of the preceding clause, characterized in that a mobile inert gas supply (70) can be used to fill the at least one inert gas lock intermediate space or the container (6, 11, 17) with inert gas.

Claims

Apparatus (1) for producing three-dimensional objects (2) by successive consolidation of layers of a building material (3) which can be consolidated by means of radiation at the points corresponding to the respective cross section of the object (2), - having a housing (4) enclosing a process chamber (5), - a construction container (6) accommodated therein, - an application apparatus (7) for applying layers of the building material (3) to a carrying apparatus (8) in the construction container (6) or a previously formed layer having a coating element (9), wherein - the construction container (6) is provided with an inert-gas-tight lid device (22), by means of which the construction opening of the construction container (6) can be covered in an inert-gas-tight manner when the construction container (6) is removed from the apparatus (1), characterized in that - an inert-gas lock (40) is arranged in the region of the at least one lid device (22), wherein - a cover device of a process chamber bottom and the cover device (22) of the construction container (6) form two walls of the inert gas lock (40), wherein - an intermediate space (41) defined by these walls forms a lock space which is provided with an inert gas inlet, such that - the intermediate space (41) between the two cover devices (22) can be flooded with inert gas before opening at least one cover device (22) and / or can be pressurized with an inert gas overpressure.Device according to claim 1, characterised in that the cover device (22) is configured to maintain an inert gas atmosphere in the construction container (6) over a longer period of time.Device according to claim 1 or 2, characterised in that the cover device (22) ensures that defined conditions can be maintained in the interior region of the construction container (6).Device according to claim 3, characterised in that the cover device (22) is ensured that a defined gas pressure can be maintained in the interior region of the construction container (6).Apparatus according to one of the preceding claims, characterized in that in the region of the construction surface opening (18) arranged above the construction container (6) located in the apparatus, an inert gas-tight cover device (30) is arranged in the process chamber base (21), which cover device seals off the construction surface opening (18) in an inert gas-tight manner when the construction container is removed from the apparatus (1).Device according to one of the preceding claims, characterized in that the opening and / or closing movement of the cover devices of the construction container (6) and / or of the construction surface opening (18) can be automated or carried out automatically.Device according to one of the preceding claims, characterized in that the cover device(s) (22, 31) comprises or comprise at least one sliding cover or at least one rolling cover (33).Device according to one of the preceding claims, characterized in that the cover device (22) is designed as at least one plate element which can be inserted into a sealing region of the construction container (6) and / or of the construction surface opening (18).Device according to one of the preceding claims, characterized in that the movements of the at least one cover device (22) can be controlled by electric motor, hydraulically or pneumatically.Device according to one of the preceding claims, characterized in that the opening or closing movement can be positively controlled by a mechanical control element on the at least one cover device (22) and / or on a holding device of the device (1) receiving the container (6, 11, 17).Device according to one of the preceding claims, characterized in that the inert gas lock (40) comprises at least one first and at least one second inert gas-tight cover element and the movement of the two cover elements can be controlled separately from one another or the cover elements can be brought into the sealing position separately from one another.Device according to claim 11, characterised in that the inert gas intermediate space (41) between the first and the second cover element of the inert gas lock (40) has an inert gas inlet.Device according to one of the preceding claims, characterized in that an overflow container (17) and / or a metering container (11) is / are formed with a lid device.Device according to one of the preceding claims, characterized in that all containers (6, 11, 17) of the device (1) are covered by the same cover element.Device according to one of the preceding claims, characterized in that the at least one cover element of the device (1) is prestressed in a closed position which is tight against inert gas by means of at least one elastic element.Device according to one of the preceding claims, characterized in that the cover device (22) has a seal, in particular an inflatable seal.Device according to one of the preceding claims, characterized in that the at least one inert gas lock intermediate space or the container (6, 11, 17) can be filled with inert gas by means of a mobile inert gas supply (70).Device according to claim 17, characterised in that the mobile inert gas supply (70) is or comprises a pressure bottle.Device according to one of the preceding claims, characterized in that the construction container (6) can be removed from the device (1) either as a separate replaceable container or within a replaceable module.Device according to one of the preceding claims, characterized in that inert gas is applied to the process chamber during the construction process.Device according to one of the preceding claims, characterized bya module cover element, wherein a plurality of containers are arranged next to one another in a removable construction module, wherein all containers are covered by a common cover element in an inert gas-tight manner.Device according to one of the preceding claims, characterized in that individual cover elements are also provided for the respective containers.Method for operating a device (1) for producing three-dimensional objects by successive solidification of layers of a build-up material which can be solidified by means of radiation at the locations corresponding to the respective cross section of the object, comprising: opening or closing an opening of a construction container, overflow container or metering container with an inert-gas-tight lid device (22) which seals the opening of the respective container (6) in the state removed from the device (1) in an inert-gas-tight manner, wherein a device (1) according to one of the preceding claims is used.

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